Feed delivery system for a froth settling unit

ABSTRACT

Embodiments of a feedwell discharge a solvent treated bitumen-containing froth feed to a froth settling vessel at a Richardson number less than 1.0. Feed is discharged from feedwell inlets to the vessel, either located at a center of the vessel or at a perimeter wall of the vessel along a substantially horizontal path across the vessel. The high velocity maximizes the horizontal path. As the velocity is reduced along the path and as a result of collision in the vessel with the perimeter wall or with feed entering the vessel from an opposing inlet, the feed separates into diluted bitumen and solvent which rises in the vessel for discharge as an overflow product and a waste stream, comprising water, solids and asphaltenes, which settles to the bottom of the vessel to be discharged as an underflow. A relatively uniform clarification zone forms above the inlets submerged in the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patentapplication Ser. No. 61/889,692, filed, Oct. 11, 2013, the entirety ofwhich is incorporated herein by reference.

FIELD

Embodiments disclosed herein relate to feed delivery systems forseparation vessels and, more particularly, to a high velocity feedwellfor a froth separation vessel.

BACKGROUND

Separation vessels are well known in a variety of industries, such asfor separation of solid particles from a liquid phase. Gravityseparators typically separate solids by gravity settling, creating agenerally quiescent environment in the vessel so as to minimize bulkfluid flux for minimizing the effect of terminal velocities of thecomponents therein. The solids are generally discharged from a bottom ofthe vessel and the clarified fluid is discharged from a top of thevessel.

In the case of extraction of bitumen from mined oil sands, the oil sandis typically mixed with water, which may be hot, for forming a slurry.The slurry is conditioned and delivered to a primary settling cell(PSC). Droplets of bitumen separate from the majority of the solidstherein which settle by gravity and rise to the top of the PSC as afroth. Typically about 10% of the slurry feed stream becomes froth. Thefroth typically comprises about 55 wt % bitumen, 35 wt % water and 10 wt% fine solids. The froth is thereafter removed from the PSC for furthertreatment to remove the water and the fine solids. As is well understoodin the industry, the froth is diluted with a solvent, naphthenic orparaffinic, and is separated in a froth settling unit (FSU) to producediluted bitumen as the product stream. Typically, about 80% of the feedstream to the FSU becomes diluted bitumen.

It is known by those skilled in the art that, in paraffinic frothtreatment, asphaltenes are precipitated and form aggregates, prior toreaching the FSU, which may trap some of the fine solids therein. Thenegatively buoyant aggregates, as well as the coarser solids and watersettle within the FSU and the cleaned, solvent-diluted bitumen product(dilbit) is removed from the top of the FSU.

It is also well known to deliver a feedstream to separation vesselsusing a feedwell. Conventional feedwells for delivering feed to theseparation vessel are often a single, vertical pipe design with adeflector plate spaced from the discharge end for distributing theslurry feed radially to the vessel.

In the case of PSCs, feedwells are known for delivering the conditionedslurry feedstream, which typically comprises bitumen, water and bothcoarse solids (≧44 um) and fine solids, (≦44 um). As one of skill in theart will appreciate, the feed stream, being the conditioned slurry, hassignificantly different settling properties than the solvent-dilutedfroth. Generally the slurry, which comprises the about 55% bitumen, 10%solids and 35% water, does not contain solvent or asphaltenes and isprimarily the result of an effort to separate bitumen from tailings andis not directed, at this stage, to product quality.

In the case of Canadian Patent 2,734,811, to Imperial Oil Resources, aPSC feedwell comprises a centrally located feedwell, typicallypositioned near a top of the vessel. The PSC feedwell has a bottomdeflector plate and a protector plate to improve the underwash layerstability. The protector plate has ventilation openings which reduce thedischarge velocity, limit the formation of an adverse pressure gradientand encourage circumferential distribution. Thus, energy in the feed isdissipated within the feedwell and the feed is delivered radiallyoutwardly therefrom rather than being directed downward toward thevessel underflow before separation of the froth from the tailings canoccur.

In Canadian patent application 2,809,959 to Syncrude, a central PSCfeedwell is designed to deliver slurry toward the center of a pluralityof inclined plate assemblies.

In the case of delivery of solvent-diluted froth to an FSU, Canadianpatent 2,672,004 to Imperial Oil Resources Limited (IOL) teachesdelivering the feed to the FSU through one or more side wall ports inthe FSU, preferably situated about half the height of the vessel andentering normal thereto, which deliver the feed such that it flows downthe inside wall of the vessel. The feed delivery is at low velocity andis characterized by a Richardson number of greater than 1.0. The gentleflow of the feed to the FSU vessel is purported to mitigate upward fluxof the smaller particles, such as mineral solids, by trapping thesmaller particles below the larger particles, such as the asphalteneaggregates which formed as a result of dilution with a paraffinicsolvent in the feed line prior to the FSU. The minerals solids are thuscarried to the discharge of the vessel by the larger particles. Further,efforts were made by IOL to design the side-inlets in such a way as tohave a reduced Reynolds number, about 2500 to 35000, at the vessel.

Conventionally, large scale settler, typically clarifiers or thickeners,have a low height to diameter aspect ratio, such as about 1:10, whereinenergy dispersion and creation of a zero vertical flux zone are key toeffective settling therein. As such, turbulence, if formed in thevessel, may result in ejecting bulk fluid from the vessel withoutseparation. FSU height to diameter ratio is typically between about1:0.5 to 1:2.

Clearly there is interest in apparatus for feeding a bitumen-rich feedto a separation vessel so as to support the separation of solids andliquids in the vessel for producing a product overflow stream which issubstantially free of fine solids and water, while at least minimizingthe cross-sectional area of the vessel required to do so.

SUMMARY

Embodiments of FSU taught herein deliver feed to a separation zonewithin the FSU vessel at a Richardson number less than about unity formaximizing the flow path in the separation zone. In embodiments, thefeed is discharged into the separation zone at a Richardson numberbetween about 0.001 to about 0.8.

In one broad aspect, a method for treating a bitumen-containing,paraffinic froth feed containing a solvent-diluted bitumen, water,solids and asphaltenes in a froth settling vessel comprises deliveringthe feed to a separation zone within the vessel. The feed is dischargedinto the separation zone, through one or more inlets, each inletdischarging the feed at a high velocity for forming a coherent streamalong a flow path generally horizontally toward a boundary and having aRichardson number less than about unity for maximizing the flow path inthe separation zone. The flow velocity of the flow path dissipatesadjacent the boundary for separating the feed into a diluted bitumen andsolvent product which rises to a top of the vessel and a waste streamcomprising water, solids and asphaltenes which settles by gravity to abottom of the vessel.

In another broad aspect, a system for separating a feed into a dilutedbitumen and solvent product stream and a waste stream comprises asettling vessel having an upper cylindrical portion and a conical bottomportion, the product stream being discharged as an overflow therefromand the waste steam being discharged as an underflow therefrom. Afeedwell, having one or more inlets to the vessel, delivers the feed toa separation zone within the vessel for discharging the feed into theseparation zone through one or more inlets, each inlet discharging thefeed at a high velocity, having a Richardson number less than aboutunity. A coherent stream is formed along a flow path generallyhorizontally toward a boundary for maximizing the flow path in theseparation zone. The velocity dissipates at about the boundary forseparating the feed into the product stream which rises to a top of thevessel and the waste stream comprising water, solids and asphalteneswhich settles by gravity to a bottom of the vessel.

Un-coalesced water droplets are carried above the separation zone andare coalesced in a coalescing zone above the separation zone. Thecoalesced water droplets fall by gravity through the separation zone, tosettle at the bottom of the vessel, carrying suspended solids associatedtherewith.

The inlets which discharge feed into the vessel are arranged about thecenter or axis of the vessel for directing the feed outwardly toward theperimeter of the vessel. Alternatively, the inlets are arranged at theperimeter of the vessel for directing the feed inwardly toward the axis.The inlets can be normal to an inlet pipe or angled or tangentialrelative to the inlet pipe.

FSU according to embodiments taught herein have a reduced footprint aswell as reduced costs associated therewith. Costs are reduced includingone or more of reducing the foundation structure required to support thevessel weight, including the weight of the contents, lowering the amountof solvent inventory required, reducing the de-inventory storagefacility size and better controlling of the system having a smaller sizevessel and reduced residence time.

BRIEF DESCRIPTION OF DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application with color drawing(s)will be provided by the Office upon request and payment of the necessaryfee.

FIG. 1 is a schematic representation of a froth separation vessel havinga feedwell for delivering a diluted froth stream therein according to anembodiment taught herein;

FIGS. 2A-2D are plan views of a plurality of alternate embodiments ofthe feedwell of FIG. 1;

FIG. 3 is a perspective view of a feedwell according to an embodimenttaught herein, inlets for delivering the diluted froth being directedtoward a center of the vessel;

FIG. 4 is a perspective plan view of the feedwell of FIG. 3, the inletsfor delivering the diluted froth being directed generally tangential tothe vessel for delivering the diluted froth circumferentially therein;

FIGS. 5A and 5B are side and front views, respectively, of an inlethaving dye discharged therefrom;

FIGS. 5C and 5D are side views of the vessel of FIG. 1, dye beingdischarged from the inlets for illustrating the flow of fluid deliveredtherefrom;

FIG. 6A1 is a vertical slice of a CFD (Computational FluidDynamics—ANSYS® fluent) simulation, illustrating a vertical velocitycomponent in mm/min, ranging from −3000 to +3000, feed being introducedto the vessel from inlets at about a center of the vessel and directedtoward a perimeter wall of the vessel;

FIG. 6A2 is a line drawing representative of FIG. 6A1;

FIG. 6B is a plan view according to FIG. 6A2, sectioned above theinlets;

FIG. 6C1 is a vertical slice of a CFD simulation illustrating a verticalvelocity component in mm/min, ranging from −3000 to +3000, feed beingintroduced to the vessel from inlets at about the perimeter wall of thevessel and directed toward the center of the vessel;

FIG. 6C2 is a line drawing representative of FIG. 6C1;

FIG. 6D is a plan view according to FIG. 6C2, sectioned above theinlets;

FIG. 7 is a plot illustrating the relationship between Richardson numberand the ratio of the superficial flux rate to the settling rate in avessel including extrapolation to a Richardson number of about 0.9,utilizing an embodiment of a feedwell which discharges froth from acenter of an FSU vessel horizontally outwardly toward a perimeter wallthereof;

FIG. 8 is a plot illustrating the relationship between Richardson numberand the ratio of the superficial flux rate to the settling rate in avessel, and extrapolation therefrom to a Richardson number of about 0.9,utilizing an embodiment of a feedwell which discharges froth from theperimeter wall of the FSU vessel horizontally inwardly toward the centerof the vessel;

FIG. 9 is a plot according to FIGS. 7 and 8, illustrating the comparisonof modelled data and extrapolated data between feedwells which dischargefrom the center of the vessel toward the perimeter wall and from theperimeter wall toward the center of the vessel;

FIG. 10 is a comparison plot illustrating the relationship betweenRichardson number and the ratio of the superficial flux rate to thesettling rate in a vessel at 100% capacity compared to a vessel turneddown to 30% capacity, utilizing a feedwell according to the embodimentof FIG. 8.

DETAILED DESCRIPTION

Generally, the term “feedwell” implies a structure, such as a chamberwhich is positioned within a vessel, such as a settling vessel, thechamber having inlets therefrom to the vessel. In embodiments describedherein, the term “feedwell” is used interchangeably to refer to astructure which provides the inlets to the vessel and to the inletsthemselves.

Embodiments of a feedwell 10 for a froth settling unit (FSU) or vessel12 are described herein and, in contradistinction to the prior art, adiluted bitumen froth F is delivered to the FSU in a vigorous manner andalong a flow path characterized by a low Richardson number Ri, beingless than about unity. The froth F may carry at least some insolubleasphaltenes therewith. The Richardson number Ri in a vessel is relatedto the fluid properties, spatial arrangement and the feed inletvelocity.

A low Richardson number is generally understood to represent a flowhaving sufficient kinetic energy that the feed stream exiting the inletto the vessel is coherent and generally unaffected by buoyancy.Therefore, one can determine the discharge parameters for the feed F toachieve the Richardson number Ri given characteristics of the feed F,the velocity of discharge and the areal influence on the feed F oncedelivered to the FSU vessel.

More particularly, as discussed herein, the Richardson number for theincoming feed or feed jet is based on a feedwell outlet diameter (d), afeed density (ρ-feed), a fluid density surrounding the feed zone(ρ_fluid), a velocity of the feed jet (u) and gravitational acceleration(g) as represented in the following equation:

Ri=d*g*(ρ_feed−ρ_fluid)/ρ_fluid/u ²

In embodiments, the Richardson number is in the range of 0.001 to 0.8.In embodiments, the Richardson number may be from about 0.001 to about0.5, and more particularly from about 0.001 to about 0.125.

The feed F is discharged from the feedwell 10 generally horizontally andacross the FSU vessel 12 for utilizing a substantial portion of thevessel's cross-section and achieving effective separation. Substantiallymaximum utilization of the vessel occurs at low Richardson numbers. Thesubstantially 100% utilization results from local upward velocitieswhich approach average upward velocities in the clarification zone. Thefeedwell discharges the bitumen-containing feed through one or more feedinlets 14 at a relatively high velocity resulting in the low Richardsonnumber and the coherent, generally horizontal feed stream until suchtime as the kinetic energy is dissipated and bulk separation can occur.Use of a large portion of the FSU vessel 12 enables use of smallervessels for the same feed stream, or more effective separation andhigher capacity than in conventionally sized FSU vessels. Applicantbelieves that the lower the Richardson number, at the feed inlet,particularly within the range of about 0.001 to about 0.8, the more thehydraulics of the fluid flow in the vessel 12 approach average for thewhole clarification zone and thus, the smaller the resulting FSU vessel12 cross sectional area. Thus, FSU vessels 12 utilizing feedwells 10,according to embodiments taught herein, are capable of efficientlyseparating diluted bitumen and solvent from water, solids andasphaltenes in the feed F and have a reduced footprint as well asreduced costs associated therewith.

In embodiments, for example, where the froth F is diluted with pentane(C₅), the hydrocarbon phase may comprise from about 30% to about 95% ofthe froth feed F. In embodiments where the froth F is diluted withbutane (C₄) the hydrocarbon phase may comprise about 20% to about 95% ofthe feed F. Fine particles are typically distributed in both thehydrocarbon rich phase and the aqueous phase. In the FSU 12, as theaqueous phase has a higher density (920-1400 g/L) than the hydrocarbonphase (550-750 g/L), the aqueous phase settles to a bottom 16 of thevessel 12 with the coarse particles and carries the suspended fineparticles therewith toward a vessel underflow 18. The FSU 12 istypically operated at between about 65° C. and about 150° C.

Any coarse solids in the feed F are caused to separate under gravity asthe energy in the feed F, discharged from the feed inlets 14 andresulting from the relatively high velocity, is dissipated along theflow path across an extent of the FSU vessel 12. Separated coarse andfine solids are recovered at the underflow 18 and may comprise betweenabout 0% to about 75% hydrocarbon, 0% to about 75% trapped water or acombination thereof. The hydrocarbon, when diluted with a paraffinicsolvent, contains asphaltenes. The hydrocarbon in the solid phasecontains about 20% to about 99% asphaltenes.

As one of skill in the art will appreciate, in embodiments taughtherein, the term “inlet” refers to any type of inlet 14 which is capableof delivering feed F to the vessel 12 in a stream at a velocity toresult in the specified range of Richardson number. In embodiments, theinlet 14 can be an open pipe, a nozzle or other such fluid feed deliveryapparatus, as is well understood in the art.

In an embodiment, as shown in FIG. 1, the feed F is delivered to aseparation horizon or zone Z of the froth settling unit or vessel (FSU)12 through the feedwell 10 which comprises a single, substantiallyvertical inlet pipe 20 which extends into the FSU 12. The feedwell 10extends along an axis of the vessel 12 to access the separation zone Zfor delivery of feed F through one or more inlets 14 extending radiallyoutwardly from the inlet pipe 20. The feed F is delivered from the inletor inlets 14 in a stream that is initially generally horizontallyradially outwardly toward a perimeter wall 22 of the FSU 12. A resultinggenerally horizontal flow path of feed F, exiting the one or more inlets14, has a Richardson number less than about unity. As a result of therelatively high velocity, the feed F exits in a coherent stream, whichgenerally resists separation and dispersion of the components of thestream as it enters the vessel 12. The stream remains coherent untilsuch time as the energy in the stream has dissipated, referred to hereinas a boundary P. In embodiments where the one or more inlets 14 are ator adjacent the perimeter wall 22 of the vessel 12, the boundary P is ata point approaching a center C of the FSU vessel 12, the energygenerally dissipating before opposing streams collide. In embodimentswherein the one or more inlets 14 are at about the center C of thevessel 12, the boundary P is adjacent the perimeter wall 22 of thevessel 12. The flow path is therefore maximized within the FSU vessel 12for effective separation of hydrocarbon and aqueous phases.

The separation horizon or zone is at or about a discharge of thefeedwell 10 which is positioned in the vessel 12 such that the one ormore inlets 14 are immersed in fluid contained within the vessel whereinthe fluid contains about 60% of the aqueous phase and about 40% of thehydrocarbon phase, regardless the height of the vessel 12. The FSUvessel 12 has a conical bottom 16 and a cylindrical upper portion 24extending upwardly therefrom. The conical bottom 16 of the vessel 12typically has an angle of between about 45° to about 75°. Inembodiments, a height of the cylindrical portion 24 of the vessel 12,above the one or more inlets 14 in the separation zone Z, is about aheight equivalent to a diameter of the vessel 12.

In the embodiment shown in FIGS. 1 and 2A, the one or more inlets 14 arefour, radially outwardly extending inlets 14 which are spacedcircumferentially about a bottom 26 of the feedwell's inlet pipe 20 andextend normal thereto. The inlets 14 are fluidly connected to the inletpipe 20. Feed F discharged from the inlets 14 is directed in thecoherent stream substantially horizontally outwardly toward the boundaryP at or adjacent the perimeter wall 22 of the FSU 12.

Having reference to FIGS. 2A to 2D, various embodiments are contemplatedin which the one or more inlets 14 direct the feed F along variousalternate flow paths across an extent of the vessel. In FIGS. 2A, 2B and3, the inlets 14 extend radially from the inlet pipe 20. In FIGS. 2C-2Dand 4 the inlets 14 pinwheel or extend angled, and generally tangentialto the inlet pipe 20. In the case where the one or more inlets 14 extendtangentially from the inlet pipe 20, the feed F is discharged in thecoherent stream substantially horizontally and can flow somewhatcircumferentially within the vessel forming a generally circular flowpattern therein. The boundary P is generally at or near the perimeterwall 22 of the vessel 12 generally opposing the inlet 14 to the vessel12. In embodiments, there may be as many as eight inlets 14, evenlyspaced about the distal end 26 of the inlet pipe 20.

As shown in FIG. 3, and in another embodiment, the feedwell comprisesthe single inlet pipe 20 fluidly connected at its distal end 26, by aplurality of radially outwardly extending pipes 28 each of which isconnected to a downwardly extending pipe 30. The downwardly extendingpipes 30 extend along the perimeter wall 22 of the vessel 12 or spacedinwardly and substantially parallel thereto. Each of the downwardlyextending pipes 30 has one or more of the one or more inlets 14 locatedat a distal end 32 for delivering the feed F into the FSU vessel 12. Theinlets 14 to the vessel 12 extend radially inwardly toward the center ofthe FSU 12. As the coherent stream of feed F exits generallyhorizontally from the plurality of radially inwardly extending inlets14, at a Richardson number less than about unity, and more particularlyin the range of about 0.001 to about 0.8, the path of the feed F ismaximized across the extent of the vessel to a point at or adjacent thecenter of the vessel. The centrally directed coherent stream of F fromopposing inlets 14 can collide, further acting to reduce the velocity ofthe feed F within the vessel 12. In the embodiment, as shown, fourdownwardly extending pipes 30 are used to deliver the feed to the inlets14 to the vessel 12, dividing the feed F therebetween.

As shown in FIG. 4, in a feedwell 10 configured as for FIG. 3, the oneor more inlets 14 can be rotated towards a more tangential alignment fordelivering the coherent stream of feed F therefrom in a generallycircular flow pattern.

Applicant further contemplates embodiments wherein the feed F enters thevessel 12 through one or more inlets 14 which extend through theperimeter wall 22 of the FSU vessel 12, spaced about a circumferencethereof. The feed F enters the vessel 12 at the high velocity, havingthe Richardson number of less than unity and more particularly between0.001 and 0.8. As in the case of FIG. 3, the feed F can flows generallyhorizontally across a diameter of the vessel 12. Further, collision ofthe feed F with feed F entering the vessel 12 from opposing inlets 14 oragainst the perimeter wall 22 of the vessel 12 results in a reduction ofvelocity within the vessel 12. The one or more inlets 14 can be normalto the perimeter wall 22, enter angled from normal, or substantiallytangential thereto.

Having reference to FIGS. 5A to 5D, dye tests were conducted in a modelof an FSU 12 having the conical bottom portion 16 and the cylindricalupper portion 24, as shown in FIG. 1. The dye tests illustrate theinitially coherent and generally horizontal flow path of feed Foutwardly from the one or more inlets 14 within the vessel 12. The flowpath extends substantially horizontally toward the boundary P, being ator adjacent the opposing perimeter wall 22 for maximizing horizontaldisplacement of feed F therein. Generally, as the energy which maintainsthe feed F in a coherent stream dissipates at the boundary P, separationcan occur. The less dense solvent-diluted bitumen, separated from thefeed F in the vessel 12, rises to a top 34 of the vessel 12 fordischarge as an overflow therefrom as the product. The more dense water,solids and asphaltenes settle to the bottom 16 of the vessel 12 and aredischarged therefrom as the underflow stream 18.

As shown in FIGS. 6A1 to 6D, Computational Flow Dynamics (CFD)simulations illustrate the separation and the formation of a relativelyuniform clarification zone 40 above the one or more inlets 14. Inembodiments, the vessel 12 has a height to diameter aspect ratio ofgreater than about 0.5. In embodiments, a height of the cylindricalportion 24 of the vessel 12 above the one or more inlets 14 is about thediameter of the vessel 12.

Having reference to FIGS. 6A1, 6A2 and 6B, in embodiments wherein theone or more inlets 14 are positioned at or near the center of the vessel12, feed F exits the one or more inlets 14 to the vessel 12 at theseparation horizon or zone Z in the vessel 12 as a coherent stream whichis directed to the boundary P, being at or adjacent the perimeter wall22. As can be seen, the lightest components and most dense components ofthe feed F, may begin to rise or fall, respectively, before the majorityof the coherent stream of feed F reaches the boundary P. Thereafter, atthe boundary P of the separation zone Z, when the energy is dissipatedtherefrom, dense components, such as water W, solids S and asphaltenesA, plunge generally downward in the vessel 12, under the effect ofgravity, for settling to the bottom 16 of the vessel 12. The less densecomponents, such as solvent V and bitumen B, rise in the vessel 12.

The upward and downward flows are generally segregated from the incomingcoherent stream of feed F, such as in areas within the vessel 12,between the coherent feed streams F. As one of skill will appreciate, asconstituents of the feed F begin to separate within the vessel 12, theconstituents largely avoid the more violently mixed areas of the vessel,such as near the incoming coherent streams of feed F, by rising andfalling in the areas of the vessel between the incoming feeds.

In embodiments taught herein, the segregation of the upward and downwardflows occurs without the need for baffles or other mechanical internalswhich are prone to mechanical failure, plugging and which may not berobust with respect to variances in operating parameters affecting thesizes of the upward and downward flows.

As will be understood by those of skill in the art, light components maybe carried downward with heavier components as they separate andfurther, some heavier components may be carried upward with the solventand diluted bitumen rising in the vessel 12. More particularly, as theupward flow of lighter components passes the incoming coherent stream offeed F, an upward impetus or flux is created which is sufficient tocarry some un-coalesced water droplets W therewith above the separationzone Z and into the clarification zone 40 thereabove. As the waterdroplets W in the clarification zone 40 coalesce, such as in a watercoalescing zone WC above the incoming coherent feed streams, thecoalesced water droplets W therein achieve a terminal velocitysufficient to counteract the upward flux. Thereafter, the coalescedwater droplets W fall through the separation zone Z, between theincoming coherent feed streams F to a water-rich zone 42 below theinlets 14, carrying solids S suspended in the water W therewith.Similarly, any solvent V and diluted bitumen B which is carried downwardwith the denser components, such as the bulk of the water W, solids Sand asphaltenes A, as they plunge in the vessel 12 separates from thedenser components below the separation zone Z and rises through theseparation zone Z between the incoming coherent feed streams F.

FIGS. 6C1, 6C2 and 6D illustrate an embodiment wherein the one or moreinlets 14 are positioned in, at or adjacent the perimeter wall 22 ofthe, feed F exiting the one or more inlets 14 to the vessel 12 at theseparation zone Z in the vessel 12 as a coherent stream of feed F whichis directed to the boundary P, being at or adjacent the center C of thevessel 12. Separation occurs generally as described for FIGS. 6A1, 6A2and 6B.

EXAMPLES

By way of example, an ideal FSU vessel 12 has a superficial flux rateapproaching the settling rate. The superficial flux rate is definedherein as the average upward velocity of the diluted bitumen and solventtoward the top 34 of the vessel 12. The superficial flux rate isgenerally calculated as flowrate divided by cross-sectional area of theFSU 12. The settling rate is defined herein as a terminal settlingvelocity to achieve a product being 99.5% pure within the vessel.

Having reference to FIGS. 7 to 9, based upon modelling using feedwells10, according to embodiments disclosed herein, the relationship betweenthe Richardson number and the ratio of the superficial flux rate and thesettling rate was determined at Richardson numbers less than 1.0.

More particularly, FIG. 7 represents modeled and extrapolated data usinga feedwell 10 having one or more inlets 14 to the vessel 12 whichsymmetrically and horizontally distribute the feed F from the inlets 14,at a center of the vessel 12, directing the feed F toward the perimeterwall 22 of the vessel 12.

FIG. 8 represents modeled and extrapolated data using a feedwell 10having one or more inlets 14 to the vessel 12 which symmetrically andhorizontally distribute the feed F from inlets 14, in, at or adjacentthe perimeter wall 22, for directing the feed F toward the center of thevessel 12.

The results of FIGS. 7 and 8 are summarized in FIG. 9 which illustratesthe comparison between the data, both modelled and extrapolated, foreach feedwell configuration. It is clear to one of skill in the art thatthe lower the Richardson number, regardless the configuration of thefeedwell's inlets 14 to the vessel 12, the closer the superficial fluxrate is to the settling rate, which approaches the ideal.

In designing an FSU vessel 12, the flowrate is fixed, thus the higherthe superficial flux rate, the smaller the vessel 12. By way of example,if the settling rate for solids in the ideal FSU vessel 12 is determinedto be 260 mm/min and the output is designed to be 3000 m³/hr of product,being 99.5% pure solvent-diluted bitumen, the cross-sectional area ofthe ideal FSU vessel 12 would be 192.3 m².

The size of the vessel 12 required to achieve the desiredcharacteristics is then calculated for various Richardson numbers, asshown in Table A, based upon the relationships shown in FIGS. 7 and 8.

TABLE A Richardson Avg. Superficial Flux Ideal FSU area CalculatedNumber rate/settling rate m² (100%) FSU area m² 0.001 94% 192 205 0.00284% 192 229 0.005 70% 192 275 0.1 40% 192 480 1.0 30% 192 640

Having reference to FIG. 10, a vessel 12 having one or more inlets 14thereto from a feedwell 10 directing feed F from in, at or adjacent theperimeter wall 22 of the vessel 12 toward the center of the vessel 12was used to model the relationship between Richardson number and thesuperficial flux rate in mm/min at 100% capacity in the vessel and at30% capacity.

When the capacity is turned down to 30%, the operating line is below thedesign line which indicates the vessel 12 can still perform for turndown rates.

It is clear to one of skill in the art that as the feed flow rate of theFSU vessel decreases, the Richardson number increases and the tolerablevertical flux decreases, however even at 30% capacity the resulting fluxis below the Richardson's adjusted tolerable flux and therefore,Applicant believes that embodiments described herein are effective evenwhen the operating rate of the vessel is less than 100% of the designcapacity.

The embodiments in which an exclusive property or privilege is claimedare defined as follows:
 1. A method for treating a bitumen-containing,paraffinic froth feed containing a solvent-diluted bitumen, water,solids and asphaltenes in a froth settling vessel comprising: deliveringthe feed to a separation zone within the vessel; discharging the feedinto the separation zone, through one or more inlets, each inletdischarging the feed at a high velocity for forming a coherent streamalong a flow path generally horizontally toward a boundary and having aRichardson number less than about unity for maximizing the flow path inthe separation zone, the flow velocity of the flow path dissipatingadjacent the boundary for separating the feed into a diluted bitumen andsolvent product which rises to a top of the vessel and a waste streamcomprising water, solids and asphaltenes which settles by gravity to abottom of the vessel.
 2. The method of claim 1 wherein un-coalescedwater droplets are carried above the separation zone, the method furthercomprising: coalescing of the un-coalesced water droplets in acoalescing zone above the separation zone, wherein the coalesced waterdroplets fall by gravity through the separation zone, to settle at thebottom of the vessel, carrying suspended solids associated therewith. 3.The method of claim 1 wherein the discharging the feed into theseparation zone further comprises discharging the feed at a Richardsonnumber between about 0.001 to about 0.8.
 4. The method of claim 1wherein the discharging the feed into the separation zone furthercomprises discharging the feed at a Richardson number between about0.001 to about 0.5.
 5. The method of claim 1 wherein the discharging thefeed into the separation zone further comprises discharging the feed ata Richardson number between about 0.001 to about 0.125.
 6. The method ofclaim 1 wherein the discharging the feed into the separation zonefurther comprises: discharging the feed through one or more inlets in,at or adjacent a perimeter wall of the vessel and normal thereto fordirecting the coherent stream of feed on the horizontal path toward theboundary adjacent a center of the vessel.
 7. The method of claim 1wherein the discharging the feed into the separation zone furthercomprises: discharging the feed through one or more inlets in, at oradjacent a perimeter wall of the vessel and angled relative thereto fordirecting the coherent stream of feed on the horizontal path and in acircular flow pattern within the vessel toward the boundary.
 8. Themethod of claim 1 wherein the discharging the feed into the separationzone further comprises: discharging the feed through one or more inletsfluidly connected to an inlet pipe extending into the vessel along anaxis of the vessel for directing the coherent stream of feedhorizontally outwardly therefrom on the horizontal path, wherein theboundary is a perimeter wall of the vessel.
 9. The method of claim 1wherein the discharging the feed into the separation zone furthercomprises: discharging the feed through one or more inlets fluidlyconnected to an inlet pipe extending into the vessel along an axis ofthe vessel, the one or more inlets being angled relative to the inletpipe for directing the feed on the horizontal path and in a circularflow pattern within the vessel toward the boundary.
 10. The method ofclaim 1 further comprising: positioning the one or more inlets at aheight in the vessel wherein a height of a cylindrical portionthereabove is about equivalent to a diameter of the vessel.
 11. Themethod of claim 1 further comprising: positioning the one or more inletsin the vessel wherein the inlets are immersed in fluid contained withinthe vessel wherein the fluid contains about 60% of an aqueous phase andabout 40% of a hydrocarbon phase.
 12. A system for separating a feedinto a diluted bitumen and solvent product stream and a waste streamcomprising: a settling vessel having an upper cylindrical portion and aconical bottom portion, the product stream being discharged as anoverflow therefrom and the waste steam being discharged as an underflowtherefrom; and a feedwell, having one or more inlets to the vessel,delivering the feed to a separation zone within the vessel fordischarging the feed into the separation zone through one or moreinlets, each inlet discharging the feed at a high velocity, having aRichardson number less than about unity, for forming a coherent streamalong a flow path generally horizontally toward a boundary formaximizing the flow path in the separation zone, the velocitydissipating at about the boundary for separating the feed into theproduct stream which rises to a top of the vessel and the waste streamcomprising water, solids and asphaltenes which settles by gravity to abottom of the vessel.
 13. The system of claim 12 wherein the coherentstream further comprises un-coalesced water droplets which are carriedabove the separation zone; the system further comprising: a coalescingzone formed above the separation zone wherein the un-coalesced waterdroplet coalesce, the coalesced water droplets thereafter falling bygravity through the separation zone as a result of increased diameterand terminal downward velocity, to settle at the bottom of the vessel,carrying suspended solids associated therewith.
 14. The system of claim12 wherein the feed is discharged into the separation zone at aRichardson number between about 0.001 to about 0.8.
 15. The system ofclaim 12 further wherein the feed is discharged into the separation zoneat a Richardson number between about 0.001 to about 0.5.
 16. The systemof claim 12 wherein the feed is discharged into the separation zone aRichardson number between about 0.001 to about 0.125.
 17. The system ofclaim 12 wherein the one or more inlets are submerged within theseparation zone, a height of the cylindrical portion thereabove beingabout equivalent to a diameter of the vessel.
 18. The system of claim 12wherein the one or more inlets are immersed in fluid contained withinthe vessel wherein the fluid contains about 60% of an aqueous phase andabout 40% of a hydrocarbon phase.
 19. The system of claim 12 wherein thefeedwell further comprises: an inlet pipe extending within the vesselalong an axis of the vessel, the inlet pipe being fluidly connected tothe one or more inlets to the vessel.
 20. The system of claim 19 whereinthe one or more inlets are fluidly connected to a distal end of theinlet pipe and extend radially outwardly therefrom for discharging thefeed along the generally horizontal path toward a perimeter wall of thevessel.
 21. The system of claim 19 wherein the one or more inlets extendnormal to the inlet pipe.
 22. The system of claim 19 wherein the one ormore inlets are angled or tangential to the inlet pipe for dischargingthe feed along the generally horizontal path in a circular flow pattern.23. The system of claim 19 wherein the one or more inlets are in, at orspaced from a perimeter wall of the vessel and extend radially inwardlytherefrom for discharging the feed toward a center of the vessel. 24.The system of claim 23 wherein the one or more inlets extend normal tothe perimeter wall.
 25. The system of claim 23 wherein the one or moreinlets are angled or tangential to the perimeter wall for dischargingthe feed along the generally horizontal path in a circular flow pattern.26. The system of claim 23 further comprising: an inlet pipe extendinginto the vessel along an axis of the vessel; one or more radiallyoutwardly extending pipes connected to a distal end of the inlet pipe;one or more downwardly extending pipes fluidly connected to the one ormore radially outwardly extending pipes and extending at or adjacent theperimeter wall of the vessel, wherein the one or more downwardlyextending pipes are fluidly connected at a distal end to the one or moreinlets and the one or more inlets extend radially inwardly therefrom fordischarging the feed therefrom toward a center of the vessel.
 27. Thesystem of claim 26 wherein the one or more inlets extend normal to theinlet pipe.
 28. The system of claim 26 wherein the one or more inletsare angled or tangential to the inlet pipe for discharging the feedalong the generally horizontal path in a circular flow pattern.